More than three years after he died in prison, whistle-blowing Russian lawyer Sergei Magnitsky was found guilty of tax evasion by a Moscow court Wednesday.

The posthumous trial of Magnitsky was a macabre chapter in a case that ignited a high-emotion dispute between Russia and Washington that has included U.S. sanctions against Russians deemed to be human rights violators, a ban on the adoption of Russian children by U.S. citizens and calls for the closure of Russian non-governmental organizations receiving American funding.

Magnitsky was a lawyer for U.S.-born British investor William Browder when he alleged in 2008 that organized criminals colluded with corrupt Interior Ministry officials to claim a fraudulent $230 million tax rebate after illegally seizing subsidiaries of Browder’s Hermitage Capital investment company.

He subsequently was arrested on tax evasion charges and died in prison in November 2009 of untreated pancreatitis at age 37.

His death prompted widespread criticism from human rights activists and the presidential human rights council found in 2011 that he had been beaten and deliberately denied medical treatment.

Announcing his verdict Thursday, Judge Igor Alisov said “Magnitsky masterminded a massive tax evasion scheme in a … conspiracy with a group of people,” according to the ITAR-Tass news agency.

Browder, a strident critic of the lack of transparency at top Russian companies who has been banned from Russia since 2005 as a security threat, was also found guilty in absentia along with Magnitsky of evading some $17 million in taxes. He was sentenced to nine years in prison.

“Today’s verdict will go down in history as one of the most shameful moments for Russia since the days of Joseph Stalin,” Browder said in a statement. “The worst part of today’s verdict is the malicious pain that the Russian government is ready to inflict on the grieving family of a man who was killed for standing up to government corruption and police abuse.”

Sen. Robert Menendez, chairman of the Senate Foreign Relations Committee, said Magnitsky’s posthumous conviction was “nothing short of a message to Russia’s activist community of the repercussions of opposing the state.”

“The trend toward authoritarianism in Russia and the accompanying escalation in violations of human and civil rights is reason for grave concern,” Menendez said in a statement.

Russia’s top court ruled in 2011 that posthumous trials are allowed, with the intention of letting relatives clear their loved ones’ names. But Magnitsky’s relatives said they had no desire for such a proceeding. Instead, the trial of Magnitsky underlined Russia’s strong resentment of foreign criticism of its human rights record.

The court said the verdict ends the case against Magnitsky, and his lawyer Nikolai Gerasimov said he had no authority to try for an appeal. Kirill Goncharov, the court-appointed attorney for Browder, told ITAR-Tass that “undoubtedly, today’s verdict will be appealed.”

Russia’s top investigative body in March closed its probe into Magnitsky’s death, finding that no crimes were committed. A prison doctor charged with negligence in his death was acquitted in December.